Because tension pneumothorax may be manifested by unexplained hypotension or wheezing during anesthesia, prompt diagnosis of the complication is often difficult.

The incidence of iatrogenic pneumothorax seems to ve increasing, for the procedure associated with pneumothorax such as internal jugular or subclavian venipuncture, intercostal or interscalene nerve blocks, laparoscopy, operator should be prepated to treat this potential complication without delay.

We presented one case of tension pneumothorax developed during general anesthesia perhaps resulting from inadvertent lung injury during internal jugular vein puncture.